Animal isolation and caging system

ABSTRACT

An animal isolation and caging system which maximizes cage density within a ventilated rack is provided. The rack includes at least one air exhaust plenum, and at least one canopy disposed within the rack for ventilation of the cages housed in a rack system. The rack is capable of supporting a first cage within the rack below a first canopy, and also positioning a second cage below a second canopy. The filter top of the first cage provided by the invention also provides a filter retainer having a filter top retainer wall designed to be in contact with a first canopy unit forming an enclosed space so configured as to create an enclosed space from which the animal isolation and caging system of the invention creates a zone of negative pressure so as to permit air to be drawn into an air exhaust plenum or duct from the interior of the first cage through the top of the first cage.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Division of co-pending application Ser. No.09/705,617, filed Nov. 3, 2000, entitled “Animal Isolation and CagingSystem,” presently allowed, the contents of which are herebyincorporated by reference herein.

FIELD OF THE INVENTION

This invention relates generally to an animal isolation and cagingsystem, and more particularly to an open rack system which maximizesboth cage density within the rack and useful volume within each cagewhile providing protection for both personnel attending to the systemand the animals contained within the cages from the contamination of thecages themselves and from the release of allergens, dander or othercontaminants from an individual cage or rack system housing a pluralityof cages through the use of a canopy capture system.

BACKGROUND OF THE INVENTION

Animal isolation and caging systems are well known in the art. Suchsystems include the animal isolation and caging systems provided for inthe ventilated rack systems disclosed in U.S. Pat. Nos. 5,349,923 and5,165,362 assigned to Lab Products, Inc., in which an open rack systemincluding a plurality of shelves, each formed as an air plenum, isprovided. Air ventilation is provided directly to animals within eachcage assembly by allowing air to travel within each shelf to a pluralityof predetermined positions within the rack. At least one cage levelbarrier having a filter cap is positioned in a rack, so that the rackand the air conduits integral within it removes air disposed adjacentthe filter cap. A cage guide is formed in substantially the same shapeas the filter cap and is affixed to the bottom of a shelf of the rackholding a cage so that when the barrier cage is placed within theventilated rack, it is positioned within the cage guide. The cage guideis separated from the filter cap of a cage by a distance. The air plenumshelf is provided with a vacuum to partially remove gases, dander,allergens and other compounds that originated in one or more cages andmoving to a location outside the cage.

The prior art animal isolation and caging systems are satisfactory.However, because each shelf acted as an air plenum, each shelf requireda certain height within the rack to allow for air to traveltherethrough, and due to a lack of a enclosed canopy or other gascapture system, animals as well as workers maintaining cages could beexposed to high levels of allergens, disease causing agents,inappropriate chemical signaling agents (e.g., pheromones), dander orother undesirable compounds released from the animal cages themselves orpresent in the air in proximity to the cages. The answer provided by theprior art was to proportion the combined height of each shelf and thecage guides mounted below each shelf to maximize vertical cage density,thereby maximizing the effect of negative pressure removal ofcontaminants, without providing for a means of creating a capture systemfor contaminants. Another problem provided by such prior art systems isthe use of large amounts of opaque material or metal that hinder visualinspection of a high cage density rack system. A system that provided a“see through” system that would allow an operator to more easilydetermine the condition of individual animals and the environment inindividual cages.

Filter cap assemblies for animal cages used within animal isolation andcaging systems are also well known in the art. One such filter cap isdisclosed in U.S. Pat. No. 4,640,228, assigned to Lab Products, Inc., inwhich a top body with a perforated filter cap top wall is provided. Asheet of filter material is sandwiched between a retainer and the lowersurface of the perforated filter top wall of the top body. The retaineris detachably mounted inside the filter body in flush abutment with thefilter material placed against the lower surface of the filter top wallof the top body. The retainer comprises a narrow border portion and flatcross arms which intersect at an integral central portion.

This prior art filter top was satisfactory. However, because theretainer was secured to the filter cap body on the interior of thefilter cap body, changing a filter with an animal within the cage wasinhibited because the entire filter cap required removal from the cageto remove the retainer and change the filter. Moreover, because theretainer was substantially open, the bottom side of the filter wassubstantially exposed to animals within the cage who might damage thefilter, rendering it ineffective and resulting in contamination orrequiring additional an structure such as a wire bar lid for protectionof the filter.

Another solution to the filter changing problem is found in U.S. Pat.No. 5,797,349, assigned to Lab Products, Inc., in which a filterchanging station is provided in which the filter protecting anindividual cage can be changed without opening the entire cage. Thechanging station disclosed in this prior art is, however, difficult tooperate and often results in the ripping of a used filter or theimproper placement of a new filter in the filter cap.

Another such filter cap is disclosed in U.S. Pat. No. 4,480,587,assigned to Lab Products, Inc., in which a cap body with an open topportion provided with a ledge and cross arms is provided. A filter isdetachably secured to the cap body by an overlaying protective platemember which is fastened over the ledge and cross arms using a pluralityof fasteners, such as threaded bolts which pass through holes in theplate member, filter and cap body and secured by respective nuts.

This prior art filter cap was also satisfactory. However, becauseseparate threaded bolt fasteners were used to mount the protective plateto the filter cap body, personnel changing a filter were required to usespecial tools to remove the protective plate to release the filter. Theuse of such tools required additional resources and was time-consuming.Moreover, because the cap body had a substantially open top and nospecific filter frame, the bottom side of the filter in this design wasalso unprotected from animals within the who might damage the filter andrender it ineffective during a filter changing operation. In addition,the substantially open top inhibited changing a filter with an animalwithin the cage because of the possibility that the animal could escapethrough the open top of the cage body during a filter changingprocedure.

Typically, the cages in a rack system must be removable from the racksystem to provide access to the animals for feeding and testing, and tothe cages for cleaning, maintenance and transport. However, it alsorequired that the rack air source and/or water source mate with the cageto provide air and water to the cage. To accommodate this requirement itis known in the art to provide a structure so that the valve in eachcage is connected to an air and/or water plenum on the rack by acoupling system. In such a system, each cage is connected to the plenumby pushing the cage into a rack until the coupling at the rear of thecage is connected to the coupling provided on the plenum to make matingcontact with a valve system containing connections to water and airsources. The couplings are disengaged by simply pulling the cage out ofthe rack, which closes a valve within the plenum coupling to prevent theescape and contamination of water and air.

In the prior art, cages designed for ventilated cage and rack systemsalso failed to provide for securely dividing a cage between two or moreanimals. The designs provided in the prior art, as typified by U.S. Pat.No. 6,041,741, assigned to Lab Products Inc., disclose only one sourceof food and water respectively within a given cage. This may beundesirable in those situations where it is desirable to moreeffectively utilize a cage footprint in compliance with appropriatefederal guidelines and increase occupancy of a given caging system, orin situations where dividing animals is necessary for research ends' orthe animals' welfare. Accordingly, it is desirable to provide adouble-sided ventilated caging system including a cage-level barriercage with a specific footprint that complies with appropriate federalguidelines while simultaneously being available to house a multiplicityof different animals typically used in scientific studies and separatethem into at least two compartments through use of a removable dividerelement that is contoured to the cage system and will prevent any cagedanimals from gaining purchase on the divider and chewing through it orotherwise damaging it. The compartments formed as a result of theremovable divider element being provided with individual food and watersources.

Filter top locking mechanisms have also been designed to prevent anindividual cage from being opened from within by an animal held there oraccidentally opening when a worker uncouples a cage from the plenum andthe rack in which it is located. However, these prior art designs havebeen large, cumbersome and expensive. Accordingly, it is desired toprovide a simple, self-contained animal cage locking mechanism whichenables an operator to lock a cage and keep it securely sealed yeteasily manipulated by a worker handling individual cages who needs tomaintain the cages and/or the animals within them. Such a lockingmechanism should maintain engagement despite bumping, jarring orimproper removal of an individual cage, and which should also be lesscumbersome and more easily replaced if lost or damaged.

Accordingly, it is desired to provide a animal isolation and cagingsystem which maximizes the stacking density of cages within the rack,while providing for the removal of unwanted contaminants fromcirculating in a laboratory environment, in the rack system itself, andamong cages. It is also desirable to provide a double-sided ventilatedcaging system including cage-level barrier cages that minimize the useof opaque materials or metal which hinder visual inspection of a animalisolation and caging system. It is also desired to provide a modifiedfilter cap for animal cages used in a animal isolation and caging systemwhich permits easy changing of the filter while an animal is within thecage and which protects the filter in use and the filter top itself fromdamage caused by animal(s) housed in an individual cage. It is alsodesired to provide a cage design footprint that will house up to twofull grown rats in compliance with appropriate federal regulations, sucha cage design also providing for a divider element that securely dividethe cage into at least two equal compartments, each compartment havingan individual food and water source. It is further desired to provide asimple animal cage locking mechanism which enables an operator tosecurely move, transport, or manipulate an individual cage that isitself easily and inexpensively replaced.

SUMMARY OF THE INVENTION

Generally speaking, in accordance with the instant invention, an animalisolation and caging system which maximizes cage density whileminimizing the use of opaque materials and metal within a ventilatedrack is provided. The rack includes at least one air exhaust plenum, andat least one canopy disposed within the rack for ventilation of thecages housed in a rack system. The rack is capable of supporting a firstcage within the rack below a first canopy, and also positioning a secondcage below a second canopy. The filter top of the first cage provided bythe invention also provides a filter retainer having a filter topretainer wall designed to be in contact with a first canopy unit formingan enclosed space so configured as to create an enclosed space fromwhich the animal isolation and caging system of the invention creates azone of negative pressure so as to permit air to be drawn into an airexhaust plenum or duct from the interior of the first cage through thetop of the first cage.

Generally speaking, in accordance with the instant invention, a filtercap for an open-top cage is further provided. The filter cap includes asubstantially rigid filter frame bonnet adapted to cover the open top ofthe open-top cage. The filter frame bonnet includes a body portion witha perforated top, and side-walls extending therefrom forming an openbottom end. The filter cap also includes a substantially rigid filterretainer sized to fit upon the filter frame bonnet and to substantiallycover the perforated top of the filter frame bonnet, the filter retaineralso having a filter top retainer wall. The filter retainer includes atop end with perforations so as to allow the passage of air, and sidewalls extending from the top end of the filter retainer forming an openbottom end, the perforations in the filter retainer being substantiallyin alignment with the perforations in the filter frame bonnet when thefilter retainer is mounted on the top of the bonnet. The filter capfurther includes attachment means for detachably securing the filterretainer to the rest of the filter cap body to permit enclosure of asheet of filter material therebetween, the attachment means beingintegrally formed in the bonnet and the filter retainer, typically,being configured as snap rivets and or detents formed in a molded cagebody.

Generally speaking, in accordance with the instant invention, the filtercap is further configured to provide for a detachable filter top lockdesigned to secure the filter cap to the cage body of the invention. Thefilter top lock being easily released by an operator, it being readilyapparent as to whether a cage is properly secured. The filter top lockof the invention enabling an operator to securely move, transport, ormanipulate an individual cage. The filter cap of the current inventionalso includes a chew shield configured to securely attach to the filtercap through the use of a plurality of snap rivets. The chew shield beingdesigned to cover the open top of the cage body and able to preventanimals from having access to and/or damaging the filter frame, filteror filter retainer. The chew shield further having perforationssubstantially in alignment with the perforations in the filter frame.

Accordingly, it is an object of the invention to provide a animalisolation and caging system which maximizes the density of cages andanimals housed within a ventilated rack system. To maximize animaldensity the current invention provides for a double-sided ventilatedcaging system including a cage-level barrier cage with a specificfootprint that complies with appropriate federal guidelines whilesimultaneously being available to house at least two large rats of thetype used in scientific studies and separate them into at least twocompartments through use of a removable divider element that iscontoured to the cage system and will prevent any caged animals fromgaining purchase on the divider and chewing through it or otherwisedamaging it. The compartments formed as a result of the removabledivider element being provided with individual food and water sources.

Another object of the current invention being to provide a double-sidedventilated caging system including cage-level barrier cages thatminimizes the use of opaque materials or metal which hinder visualinspection of the animal isolation and caging system of the invention.

Another object of the invention is to provide a animal isolation andcaging system which does not require distinct shelving for positioningand supporting cages within the rack and which thereby maximizes theproportion of space within the rack which may be occupied by cages.

Another object of the invention is to provide for a rotatable dosagefeeder for an animal cage which selectively provides multiple exactdosages of food to an animal within a cage of the invention. The feederhas a frame dividing a cage interior side from a cage exterior side. Afood holding member is rotatably mounted on the frame and holds aplurality of measured dosages of food. At least a portion of the foodholding member extends within the cage to the cage interior side of theframe. In a preferred embodiment the food holding member is a carousel.

A further object of the invention is to provide a animal isolation andcaging system with canopies which position and support cages within therack without additional shelving and which, through canopy capturesystem, guide exhaust air drawn from cages within the rack through acanopy capture system into an air exhaust duct to remove exhaust airfrom the rack without contamination of operating personnel orcross-contamination between cages within the rack.

Still another object of the invention is to provide a filter cap for anopen-top cage which permits a filter to be securely mounted yet easilyand quickly changed with a filter removal device easily utilized by anoperator.

A still further object of the invention is to provide a filter cap foran open-top cage which permits replacement of a filter while animals arewithin the cage and which prevents such animals from escaping duringfilter replacement.

Yet another object of the invention is to provide a filter cap for anopen-top cage which protects the filter from damage caused by animalswithin the cage through the use of a chew shield.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specifications anddrawings. The invention accordingly comprises the features ofconstruction, combination of elements, and arrangement of parts whichwill be exemplified in the constructions hereinafter set forth, and thescope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is an exploded perspective view, of a single cage of the animalisolation and caging system constructed in accordance with the presentinvention;

FIG. 2 is a plan front view of a cage of the current invention showingthe diet delivery system water bottle, and cage coupling;

FIG. 3 is a top plan view of a filter cap in accordance with the currentinvention;

FIG. 4 is a side view of a cage of the current invention showing theproximity of the diet delivery system and the cage coupling;

FIG. 5 is a top plan view of a cage body of the current invention;

FIG. 6 is a side plan view of a cage body of the current invention;

FIG. 7 is a perspective view of a cage body of the current invention;

FIG. 8 is a side view of a cage body of the current invention;

FIG. 9 is a top plan view of a diet delivery system of the invention;

FIG. 10 is a front plan view of a diet delivery system of the invention;

FIG. 11 is a perspective view of a diet delivery system of theinvention, including water bottle with sipper tube;

FIG. 12 is a side plan view of a diet delivery system of the invention;

FIG. 13 is a top plan view of a filter cap of the current inventionincluding a secured filter top lock;

FIG. 14 is a side plan view of a filter cap of the current inventionincluding a rear lock tab;

FIG. 15 is a perspective view of the filter cap of the current inventionshowing the an attached filter top lock of the invention;

FIG. 16 is a front view of the filter cap of the current invention withthe filter top lock of the current invention;

FIG. 17 is a plan top view of the filter top lock portion of the animalisolation and caging system of the invention;

FIG. 18 is a plan front view of a filter top lock element of the currentinvention detached from the filter cap and cage body of the currentinvention;

FIG. 19 is a perspective view of the filter top lock element of thecurrent invention;

FIG. 20 is a plan side view of the filter top lock element of thecurrent invention;

FIG. 21 is a front view of a cage of the current invention, including apartial cutaway of the filter cap, and diet delivery system, alsoshowing a divider element separating a cage of the invention into twocompartments;

FIG. 22 is a top view of a cage of the current invention with detentsfor holding the filter retainer of the cage top onto the filter frame ofthe invention;

FIG. 23 is a side view of a cage of the current invention with a partialphantom of the divider element embodiment of the invention used toseparate a cage of the animal isolation and caging system of the presentinvention, including a view of the diet delivery systems put in placefor multiple animals when the divider element is utilized;

FIG. 24 is a plan top view of a divider element embodiment of thecurrent invention;

FIG. 25 is a plan side view of a divider element embodiment of thecurrent invention, with directional arrow A indicating the front of thecage body of the current invention;

FIG. 26 is a perspective view of a divider element of the currentinvention;

FIG. 27 is a partial cross-sectional and cutaway view of a dividerelement of the current invention;

FIG. 28 is a plan top view of a double-sided rack system embodiment ofthe animal isolation and caging system of the present invention;

FIG. 29. a plan side view of a double-sided rack system embodiment ofthe animal isolation and caging system of the present invention;

FIG. 30 a is a plan side view of a single-sided rack system of the cagelevel barrier cage constructed in accordance with the present invention;

FIG. 30 b is a front view of a single-sided rack system of the cagelevel barrier cage constructed in accordance with the present invention;

FIG. 30 c is a front view of a single-sided rack system of the cagelevel barrier cage constructed in accordance with the present invention;

FIG. 31 is a plan side view of a cage locking system for securing thecages of the current invention to a double-sided rack system of theanimal isolation and caging system constructed in accordance with thepresent invention;

FIG. 32 is a plan front view of a cage locking system for securing thecages of the current invention to a double-sided rack system of theanimal isolation and caging system constructed in accordance with thepresent invention;

FIG. 33 is a plan top view of a double-sided rack system of the animalisolation and caging system constructed in accordance with the presentinvention;

FIG. 34 is a side view of a cage locking system for securing the cagesof the current invention to a single-sided rack system of the animalisolation and caging system constructed in accordance with the presentinvention;

FIG. 35 is a front view of a cage locking system for securing the cagesof the current invention to a single-sided rack system of the animalisolation and caging system constructed in accordance with the presentinvention;

FIG. 36 is a plan top view of a cage locking system for securing thecages of the current invention to a single-sided rack system of theanimal isolation and caging system constructed in accordance with thepresent invention;

FIG. 37 is a plan top view of a double-sided rack system of the animalisolation and caging system constructed in accordance with the presentinvention indicating the emphasis on the use of see through materialsfor enhanced visual observation of the caging system and animals heldtherein;

FIG. 38 is a plan side view a double-sided rack system of the animalisolation and caging system constructed in accordance with the presentinvention indicating the emphasis on the use of see through materialsfor enhanced visual observation of the caging system and animals heldtherein;

FIG. 39 is a plan front view of a double-sided rack system of the animalisolation and caging system constructed in accordance with the presentinvention indicating the emphasis on the use of see through materialsfor enhanced visual observation of the caging system and animals heldtherein;

FIG. 40 is a front view of a cage body and diet delivery system of thecurrent animal isolation and caging system indicating the emphasis onthe use of see through materials;

FIG. 41 is a top view of a cage body and diet delivery system of thecurrent animal isolation and caging system indicating the emphasis onthe use of see through materials, without the presence of a filter capto enclose the interior of the cage body;

FIG. 42 is a side view a cage body and diet delivery system of thecurrent animal isolation and caging system indicating the emphasis onthe use of see through materials, without the presence of a filter capto enclose the interior of the cage body;

FIG. 43 is a perspective view of a cage body and diet delivery system ofthe current animal isolation and caging system indicating the emphasison the use of see through materials, without the presence of a filtercap to enclose the interior of the cage body, also showing indents incage body configuration for a rear locking tab and filter top lockrespectively;

FIG. 44 is a front view of a cage body and diet delivery system of thecurrent animal isolation and caging system indicating the emphasis onthe use of see through materials, without the presence of a filter capto enclose the interior of the cage body, also showing a divider elementseparating a cage of the invention into two compartments;

FIG. 45 is a plan top view of a cage body and diet delivery system ofthe current animal isolation and caging system indicating the emphasison the use of see through materials, without the presence of a filtercap to enclose the interior of the cage body, also showing a dividerelement separating a cage of the invention into two compartments;

FIG. 46 is a plan side view cage body and diet delivery system of thecurrent animal isolation and caging system indicating the emphasis onthe use of see through materials, without the presence of a filter capto enclose the interior of the cage body, also showing a divider elementseparating a cage of the invention into two compartments;

FIG. 47 is a perspective view of a cage body and diet delivery system ofthe current animal isolation and caging system indicating the emphasison the use of see through materials, without the presence of a filtercap to enclose the interior of the cage body, also showing a dividerelement separating a cage of the invention into two compartments;

FIG. 48 is a front view of a second embodiment of the cage of the animalisolation and caging system of the invention providing a rotatablefeeding mechanism, also including the optional presence of a dietdelivery system of the current invention;

FIG. 49 is a top view of a second embodiment of the cage of the animalisolation and caging system of the invention providing a rotatablefeeding mechanism, also including the optional presence of a dietdelivery system of the current invention;

FIG. 50 is a side view, with a partial cutaway, of a second embodimentof the cage of the animal isolation and caging system of the inventionproviding a rotatable feeding mechanism, also including the optionalpresence of a diet delivery system of the current invention;

FIG. 51 is a perspective view of a second embodiment of the cage of theanimal isolation and caging system of the invention providing arotatable feeding mechanism, also including the optional presence of adiet delivery system of the current invention;

FIG. 52 is a front view of a filter removal device constructed inaccordance with the present invention;

FIG. 53 is a top view of a filter removal device constructed inaccordance with the present invention;

FIG. 54 is a side view of a filter removal device constructed inaccordance with the present invention;

FIG. 55 is a perspective view of a filter removal device constructed inaccordance with the present invention;

FIG. 56 is a front view of a valve charging station constructed inaccordance with the present invention;

FIG. 57 is a plan top view of a valve charging station constructed inaccordance with the present invention, including the valve chargingstations location within the cage body of the current invention;

FIG. 58 is a side view of a valve charging station constructed inaccordance with the present invention, including the valve chargingstations location within the cage body of the current invention;

FIG. 59 is a partial cutaway view of the canopy capture system of thecurrent invention including indications for the flow of unwanted gasesand contaminants from above a cage body through a canopy capture channelinto a exhaust duct;

FIG. 60 is a side view of a canopy element for the rack of the animalisolation and caging system of the invention;

FIG. 61 is a perspective view a canopy for the rack of the animalisolation and caging system of the invention, including attachmentelements for connection to a ventilated rack system of the invention;

FIG. 62 is a front view of a canopy element for the rack of the animalisolation and caging system of the invention;

FIG. 63 is a top view of a canopy element for the rack of the animalisolation and caging system of the invention;

FIG. 64 is a cross-sectional view of a canopy capture channelconstructed in accordance with the present invention;

FIG. 65 is a top view of a canopy capture channel constructed inaccordance with the present invention;

FIG. 66 is a front view of a canopy capture channel constructed inaccordance with the present invention; and

FIG. 67 is a perspective view of a canopy capture channel constructed inaccordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Cage Body

Reference is first made to FIGS. 1-8, wherein a single cage of an animalisolation and caging system, generally indicated at 10, constructed inaccordance with the invention is shown. The cage assembly incorporates afilter retainer 15, a filter frame 20, a filter top lock 25, a chewshield 30, a plurality of snap rivets 35, a water bottle 40, a bottlecap 45, a sipper tube 50, a diet delivery system 55, a plurality of dietdelivery components 60, and a cage body 65. Cage body 65 comprises abox-like animal cage with a combination diet delivery system 55 capableof providing both food and water to animals within cage 10. A reusablefilter 70 is also generally provided with caging system 10 sandwichedbetween filter retainer 15 and filter frame 20.

Cage body 65 is formed with integral side walls 80, a bottom wall orfloor 82 and a open top end. The walls are preferably formed of a cleartransparent plastic such as polycarbonate, which is rigid, durable,permits observation of animals, has a high impact strength, and ismachine washable or autoclavable at temperatures under 250 degreesFahrenheit. Such a cage is conventional, commercially available, andwidely used. A standard absorbent flooring of particulate matter such aswood chips (not shown) may be spread on floor 82 of cage body 65. Theopen top of cage body 65 is bordered by peripheral lip 83 which extendscontinuously therearound. Cage body 65 may also include a plurality ofcorner structural reinforcements 84 for added structural support forcage 10. When included in a rack system 100 cage 10 may include a cagecoupling valve 75 designed to attach cage 10 integrally into rack system100 and provide water and air for animals located in an individual cage10.

Referring now to FIG. 's 21-27, another embodiment of the currentinvention provides for the placement of a removable divider element 105whose peripheral edge 106 is contoured to the cage system 10 and willprevent any caged animals from gaining purchase on divider element 105and chewing through it or otherwise damaging it. Each of thecompartments 105 a and 105 b formed as a result of the removable dividerelement 105 being provided with individual food and water sources in theform of a plurality of diet delivery components 60. Specificallyreferring to FIGS. 24-27, it can be seen that divider element 105 isprecisely contoured and molded to fit into cage body 65 and cage system10 (not shown) without disturbing the integrity of the “petri dish”configuration between filter cap 11 and cage body 65 to form an enclosedcaging system 10 capable of housing at least one animal in each ofcompartments 105 a and 105 b. Divider element 105 is configured so as toaccept the placement of at least two diet delivery systems 55 (notshown) in divider grooves 104. Though divider element 105 may beconstructed of any suitable material it is preferably formed out ofopaque plastic material, the material chosen is rigid, durable, permitsobservation of animals, has a high impact strength, and is machinewashable or autoclavable at temperatures under 250 degrees Fahrenheit.

Divider element 105, when placed in cage body 65 has peripheral edge 106in flush contact with floor 82 and at least two opposing side-walls 80(see FIGS. 21 and 23) and upper edge 14 that will be in contact with theundersurface of filter cap 11 when cage assembly 10 is closed. Dividerelement 105 has divider lips 107 that are contoured to fit withinindents 108 in cage body 65 when divider 105 is positioned along theline indicated by arrow D in FIG. 25 from the front to rear of cageassembly 10 such that the integrity of the “petri dish” configurationbetween filter cap 11 and cage body 65 to form an enclosed caging system10 is not altered. Though cage body 65 may be have a variety ofdimensions provided to house individual laboratory animals in compliancewith the provisions of the Animal Welfare Act (“AWA”)(enacted in 1966)and the Institute of Laboratory Animal Resources (“ILAR”) Guidelines(1996) specify certain space parameters for specific animal species andfor animals at specific developmental stages or weights. ANIMAL WELFAREACT 9 C.F.R. §§ Chapter 1 et seq. (1966), and as amended 7 U.S.C. §§2131 et seq.; and see, GUIDE FOR THE CARE AND USE OF LABORATORY ANIMALS,Institute of Laboratory Animal Resources (ILAR);National Academy PressWashington, D.C. (1996)(both incorporated herein by reference), the useof divider element 105 cage body 65 would be divided into compartments105 a and 105 b each of sufficient size to house a variety of animalsalso in compliance with AWA and ILAR. In one embodiment of cage assembly10 the dimensions of cage body 65 would be sufficient to provide afootprint of at least 140 square inches, preferably 140.8 square inches.This footprint is sufficient to house to large rats within the confinesof a cage assembly 10 with or without divider 105. Rack system 100 maybe configured such that 80 cages providing 140.8 square inches of floorspace each may be provided in a double-sided rack system and 36 cages ofa similar dimension in a single-sided rack system. It should beremembered that the mobile rack systems envisioned by the invention aredimensioned so as to be movable through the typical and well knowndimensions of doors in terms of width and height. Mobile rack systemsare also capable of continuously providing air and water to cages placedwithin and attached to the rack systems 100. It is also envisioned thatother animals, including mice, would be housed within the confines ofcage assembly 10 with any needed changes to cage size or dimension,including changes to divider grooves 104 or peripheral edge 106 toconform to changes in cage dimensions.

Referring now to FIGS. 9-12, the current invention provides for the useof a diet delivery system 55 for providing food and needed liquids tolaboratory animals in cage assembly 10. Diet delivery system 55 iscomposed of a water bottle 40 that typically contains water for animalsconsumption but may be used to provide liquids other than pure water,and diet delivery components 60. Components 60 may be utilized toprovide solid food to animals within cage assembly 10. Diet deliverysystem 55, bottle 40, and components 60 may be composed of any materialor combination of materials, typically plastics with some machined metalfeatures such as a metal wire food holder element 61 or bottle holderelement 62. Diet delivery system 55 has flanges 63 that fit within cagebody grooves 64 to securely hold diet delivery system within cage body65 and above the floor 82 (not shown) so that food and water areaccessible to animals within cage 10. Cage body grooves 64 are contouredsuch that when flanges 63 of diet delivery system 55 are placed thereinfilter cap 11 of cage assembly 10 can be easily closed and sealed withfilter top lock 25 (not shown).

In alternate embodiment according to the invention diet delivery system55 and bottle 40 may be made of clear plastic such that observation ofanimals in cage assembly 10 is optimized. In this instance holderelements 61 and 62 may still be composed of machined metal but in thisembodiment the machined metal portions of holder elements 61 and 62 arereduced to the lower portions of components 60 with the upper body 66 ofcomponents 60 made of clear or non-metallic material.

Referring now to FIGS. 31-47, another embodiment of cage assembly 10 andrack system 100 is construction of a cage assembly 10 and rack system100 that emphasizes the use of clear materials that would allow anoperator to more easily determine the condition of individual animalsand the environment in individual cages. In this embodiment the plasticsutilized by a manufacturer to produce cage assembly 10 and rack system100 would be clear, not opaque, and metallic components would be limitedas possible, including chew shield 30 and cage coupling 75. Moreover,rack system 100 would utilize high impact plastics materials in airsupply plena 110, air exhaust plena 120, and open rack 115.

Rack System

Referring now to FIGS. 28-39, an animal isolation and caging rack system100 of the invention includes an open rack 115 having a left side wall125 and a right side wall 130, a plurality of rack coupling stations 16,a top 135, and a bottom 140. A plurality of posts 145 are disposed inparallel between top 135 and bottom 140. Vertical posts 145 arepreferably narrow and may comprise walls extending substantially fromthe front of rack 115 to the rear of rack 115, or may each comprise twovertical members, one at or near the front of rack 115 and the other ator near the rear of rack 115. Rack system, in accordance with theembodiments of the current invention, may be a one-sided rack systemwith regard to cage assemblies placed therein as seen in FIGS. 30 a-cand 34-36 or two-sided as seen in FIGS. 31-33 and 37-39.

Animal isolation and caging rack system 100 also includes a plurality ofair supply plena 110 and air exhaust plena 120 alternately disposed inparallel between left side wall 125 and right side wall 130 in rack 115.Air is forced into air supply plena 110 by at least one control unit 150through an air supply conduit 151, said air supply conduit 151communicating with each air supply plenum 110 through a side wall of therack 115. A control unit 150 preferably communicates with a blower 155(not shown) and at least one rack air filter 158 for supplying filteredair to rack 115 and a plurality of cage level barrier cage assemblies10. Air is withdrawn from air exhaust plena 120 by a vacuum 160 throughair exhaust conduit 165, said air exhaust conduit 165 communicating witheach air exhaust plenum 120 through a side wall of the rack 115. Aplurality of cage level barrier cages (cages 10) may be positionedwithin rack 115. Each cage is formed of a gas impermeable floor 82having an upstanding sidewall 80 and a filter cap 11.

Now referring to FIGS. 13-16 and 59-67, a plurality of cage assemblies10 are positioned within rack 115 by canopies generally indicated at170. Each canopy 170 shrouds a cage assembly 10 a below a canopy 170.Accordingly, each canopy 170 is shaped and positioned so as to come intosubstantial contact with peripheral lip 83 which extends from the upperwall 23 of filter retainer 15 from a cage assembly 10 a. Accordingly,with the substantial contact between lip 83 and a canopy 170 there isthe creation of an exhaust zone 175 above filter cap 11 of cage assembly10 a. Unwanted gasses and contaminants including allergens, dander, dustand ammonia moving into exhaust zone 175 from cage assembly 10 a aremoved from exhaust zone 175 through exhaust channel 95 across canopycapture element 90 forming a canopy capture channel “C” into an exhaustduct 165 or exhaust duct 165 a. This movement is initiated through thecreation of a negative pressure in exhaust zone 175 by a vacuum 160 (notshown). The placement of a cage assembly 10 a in rack 115 causes anengagement between the upper surface of filter cap 11 and canopy captureelement 90. This exhaust of contaminants or unwanted gasses protectsanimals in each of the cage assemblies 10 present in a rack 115 throughthe individual venting of exhaust zone 175 and also protects operatorsutilizing the animal isolation and caging system of the invention fromexposure to allergens or other contaminants.

Canopy capture element 90 maintains a short gap h between the top 23 offilter cap 11 and canopies 170. Gap h should be sufficient to allowmovement of gases between canopy 170 and filter cap 11, and in anexemplary embodiment gap h is {fraction (1/16)} of an inch to ¼ of aninch. Canopy 170 profiles filter cap 23 and overlaps overhangs lateralperipheral flange 88 of filter cap 11, preferably creating a tension fitagainst the sidewall 80 of cage body 65. The rear of canopy captureelement 90 is attached to air exhaust duct 165 or air exhaust plenum120.

Canopies 170 are disposed in parallel columns in rack 115 between eachpair of adjacent posts 145, or between left side wall 125 and anadjacent post 145, or between right side wall 130 and an adjacent post145. Each canopy 170 supports a first cage 10 a above the canopy 170 inthe rack 115 and shrouds the filter cap 11 of a second cage 10 b belowthe canopy 170 in the rack forming a exhaust zone 175 with peripherallip 83. The floor 82 of a cage assembly 10 of the first cage 10 a restson top of the corresponding canopy 170. Of course, those canopiespositioned at the top row of rack 115 do not support a cage assembly 10above them, and those cages 10 positioned on the bottom row of rack 115are preferably supported by bottom 116 of rack 115. When positioned inthe rack, each cage assembly 10 communicates with air supply plenum 120through a cage coupling 75. Such cage couplings 75 are known in the art,and are disclosed, for example, in U.S. Pat. Nos. 4,989,545 and5,042,429 assigned to Lab Products, Inc. Air supply plena 120 may alsoinclude means for delivering a supply of water to cage assemblies 10through cage coupling 75, as is also known in the art. Canopies 170 arepreferably constructed of a lightweight, transparent material which issubstantially rigid, such as clear plastic. Such clear plastic canopiesprovide enhanced visibility of cage assemblies 10 within rack system 100and reduce the overall weight of rack system 100.

Referring in particular to FIG. 28, a cage 10 is positioned within rack115 and coupled to an air supply plenum 110 a through cage coupling 75.Blower 155 forces air into the air supply plenum 110 a in the directionof arrow A, and air is consequently forced into cage 10 through cagecoupling 75 in the direction of arrow B to supply air to animals withinthe cage assembly 10. Vacuum 160 withdraws air from air exhaust plenum120 through canopy capture channel C into exhaust channel 95, therebycreating a negative pressure within the exhaust zone 175. Ducts 166 areformed in air exhaust plena 120 below the position at which canopy 170is attached and communicating with gap h, permitting air in exhaust zone175 to be drawn into air exhaust plena 120 causing a negative pressurewithin the space defined by peripheral lip 83 and canopy 170.

Referring to FIGS. 60-63, a first embodiment of canopy 170, generallyindicated at 170 a, comprises a top plate 171. Top plate 171 is attachedto canopy capture element 90 and is in communication rack 115 (notshown) at an air exhaust plenum 120 (not shown). Top plate 171 hascanopy capture sidewalls 172 which extend below the filter frame outeredge 33 of filter cap 11. Sidewalls 172 are disposed so as to extendunderneath at least a portion of the overhang of outer edge 33 andfilter cap 11.

Canopy 170 a is preferably mounted to air plenum 120 at the rear and totwo posts 145 at the front of rack 115. Each post 145 preferablycomprises a vertical T-beam, with a first face 145 a being disposedsubstantially parallel to the direction of insertion of a cage assembly10 into rack 115, and a second face 145 b being disposed substantiallyperpendicular to said direction of insertion. Each side of face 145 b isprovided with notches 145 c for supporting canopy 170 a therein. Tomaximize horizontal cage density within rack 115, notches 145 apreferably extend as close to face 145 a as possible, and face 145 a ofpost 145 is preferably made as narrow as possible while still providingstructural support for rack 115. By providing such a notched T-beam post145 on each side of canopy 170 a, canopy 170 a may be supported on bothsides from the front of rack 115. Other means of providing the supportof posts 145 are contemplated by the invention. For example, a notchedL-beam post 145 could be used, thereby providing support to only oneside of canopy 170 a from the front of the rack, or canopies 170 a couldbe screwed to a flat vertical panel disposed parallel the cage insertiondirection and extending from the top to the bottom of rack 115.

Accordingly, because each canopy 170 acts as both a support for the cageassembly 10 above it in rack 115 as well as a shroud over the filter capof the cage 10 below it in rack 115 which guides exhaust air intoexhaust conduit 165 from the cage 10 as well as ambient air into the airexhaust plenum 120, additional shelving is not needed to position andsupport cages 10 within rack 115. As a result, cages 10 may bevertically positioned closer together in rack 115 than in a rack havingdistinct shelving, thereby advantageously increasing the stackingdensity of cages 10 within rack 115.

Now referring to FIGS. 56-58, an embodiment of the current inventionincludes a valve charging station 400 connected to rack system 100through a air conduit 401. Charging station 400 provides for theconsistent movement of pressurized air for the cage assemblies 10 of anopen rack 115, through a plurality of air supply plena 110. Air movesthrough nozzle assembly 402. Charging station 400 may also be locatedintegral to a rack system 100.

Filter Cap

Reference is now made to FIGS. 13-16, in which a filter cap, generallyindicated at 11, for an open-top cage, such as cage 10 described above,and fitting within rack system 100 constructed in accordance with theinvention is shown. Filter cap 11 is configured to cover the top of acage floor 82 (not shown). Filter retainer 15 has a top ridge 85 whichextends substantially around the top of filter retainer 15, having anexhaust channel 95 moving in the direction of Arrow D, for canopycapture element 90 to remove unwanted gases and contaminants from thecage 10 when cage 10 is incorporated in rack system 100 (not shown).Cage floor 82 may also include corner structural reinforcements 84 foradded structural support and for stacking a plurality of cages bottoms(not shown).

Filter cap 11 may be formed as a layered construction including a filterretainer 15, a reusable filter 70, a filter frame 20, a chew shield 30of layered construction 11 held together to filter frame 20 by aplurality of snap rivets 35. Snap rivets 35 may be constructed of manymaterials but must be durable, preferably snap rivets 35 are constructedof nylon or metal. Filter retainer 15 is preferably formed of clearplastic which is substantially rigid but permits a modest degree offlexure when torsional forces are applied thereto. As shown in FIGS.13-16, filter retainer 15 has a perforated top wall 21 which isintegrally molded with a top ridge 85 extending substantially around thetop of filter cap 11. Top wall 21 is provided with a plurality ofperforations 23, preferably of generally square configuration andforming a grid array. Respective opposed pairs of filter side walls 24depend substantially orthogonally from top wall 21. The surface formedon filter retainer 15 for resting filter cap 11 on cage floor 82includes a continuous lateral peripheral flange 88 extending generallyperpendicularly outwardly from side walls 24. Lateral flange 88 servesto encompass and detachably secure to filter frame 20. Ribs 91 extendfrom flange 88 to allow stacking of the filter retainer 15.

Referring to FIGS. 1 and 13-16, Filter cap 11 is also provided with afilter frame 20. Filter frame 20 is preferably formed of material havingthe same properties as those of filter retainer 15 described above butwith a different rigidity. Filter frame 20 detachably and securelymaintains an air filter 70 (not shown) to the undersurface of top wall21. Filter frame 20 includes a generally flat perforated top wall 31.Top wall 31 includes a substantially rectangular body portion 32. Anouter flange 33 of body portion 32 depends from filter frame 20. Acontinuous peripheral flange 34 depends from outer peripheral flange 33.

In FIG. 16, flange 33 is spaced from, encompasses and overhangs lip 83of cage body 65 (not shown). Thus, filter cap 11 cannot be inadvertentlydislodged from cage body 65 and must be lifted off to be removed. Itshould also be noted that the clearance space between flange 33 and lip83 should permit only a slight movement of filter cap 11 on cage body65. However, outer flange 33 is preferably of sufficient lateral extentto remain in contact with lip 83 despite any relative lateral movementbetween filter cap 11 and cage body 65, thereby maintaining theintegrity of the “petri dish” configuration between filter cap 11 andcage body 65 to form an enclosed caging system 10 capable of housing atleast one animal.

To prevent animals placed within cage assembly 10 from damaging the cageor any of filter cap 11's components the current invention provides chewshield 30 integrally connected to the underside of filter frame 20 bythe use of a plurality of snap rivets 35. Chew shield 30 is designed toallow the passage of air and other gasses but to prevent any animalsfrom within cage 10 from gaining purchase on other components of thefilter cap 11. Chew shield 30 is preferably constructed of metal andextends into the upper area of cage body 65 inside sidewalls 80 toreduce any lateral movement of filter cap 11 relative to cage body 65.

In a preferred embodiment, air filter 70 is a thin sheet of spun-bondedpolyester of the type sold by DuPont under the trademark REEMAY 2024. Afilter thickness of between 10 and 15 millimeters has been foundadequate for a filter having an area approximately equivalent to thearea of filter retainer top wall 21. Air filter 70 is mounted on the topsurface of filter frame 20 and is held in place by filter retainer 15 ina manner to be now described. REEMAY 2024 is used by way of example onlyand any filter medium having at least its properties or similarproperties may be utilized.

Filter cap 11, air filter 70 is placed against the top wall 31 of filterframe 20 of filter cap 11. Thereafter, filter retainer 15 is mountedatop filter frame 20. Top wall 31 of filter frame 20 is provided withperforations 34 which are preferably substantially coextensive and inalignment with perforations 23 in top wall 21 of filter retainer 15 whenfilter frame 15 is mounted atop filter frame 20. The mesh structure oftop wall 31 serves to prevent air filter 70 from sagging and holds airfilter 70, while filter frame 20 holds filter 70 securely in placeagainst the top surface of top wall 21. In the assembled filter cap 11,perforated top wall 21 overlies filter 70 to protect the filter 70against damage during handling and prevent its movement or buckling,while filter 70 rests flush upon perforated top wall 31 of filter frame20 which supports and protects air filter 70 in its mounted position.Additionally, touching the filter 70 with fingers may destroy the filterintegrity, and therefore the perforated walls 21 or 31 respectively oneither side of the filter 70 prevent contact with the filter by thetechnician during handling and also prevents contact with the filter bythe animal. The lower region of filter cap 11 is further protected fromanimal damage by the use of chew shield 30. Chew shield 30 beingattached to filter frame 20 through the use of a plurality of snaprivets 35 (not shown).

Filter retainer 15 is held in place by means of small projections ordetents 51 which are integrally molded on the outer surface of filterframe body 32. Four spaced detents 51 are molded on each long sidefilter frame body 32 of filter cap 11, and two spaced detents 51 aremolded on each shorter filter frame body 32. Each of the detents 51 hasa convex or arcuate free end. Similarly, apertures or slots 52 areformed in filter frame body 32 of filter frame 20 which are positionedand dimensioned so as to snugly receive detents 51 when filter retainer15 is mounted on filter cap 11. In an alternative embodiment, detents 51could be formed on the inner surface of filter frame body 32 of filterframe 20, while slots 52 would be formed in side walls 53 of filter cap11. It is also possible to dimension filter retainer 15 to be held tofilter frame 20 by a tension fit.

Detents 51 are precisely molded on filter frame 20 and are spaced fromthe top surface of peripheral flange 88 by a distance slightly greaterthan the height of integral peripheral flange 88 of the filter frame 20.After air filter 70 has been positioned against the bottom surface oftop wall 21, filter retainer 15 is moved downwardly upon filter frame 20toward the perforated top wall 21 thereof to permit detents 51 to engageslots 52. Filter frame body 32 of filter frame 20 flex outwardly to themounted position. At the same time, the meshed structure of perforatedtop wall 31 of filter frame 20 engages the lower surface of air filter70 and presses filter 70 firmly against the lower surface of top wall 21of filter retainer 15. Air filter 70 is thus sandwiched between filterretainer 15 and the top surface of top wall 32 of filter frame 20, andmay be retained in this mounted position by the engagement of detents 51with filter retainer 15.

Filter retainer 15, filter frame 20 and air filter 70 may thus be firmlylocked in a mounted position so that they cannot be accidentallydislodged during autoclaving or handling. An assembled filter cap 11 canthus be lifted and removed from cage body 65 for all normal functionssuch as feeding, treating or examining animals therein withoutdisturbing or dislodging air filter 70.

Filter Removal Device

Referring to FIGS. 52-55, when it becomes necessary to replace or removefilter 70 from filter cap 11, another of embodiment of the currentinvention provides a filter removal device 200, constructed inaccordance with the invention is shown. Filter removal device 200includes a base board 201, and a first guide support 205 and a secondguide support 210 mounted thereon in facing relationship. A respectiveseparator 202, 203 is mounted on an outer surface of a respective guidesupport 204, 206.

Base board 201 is formed with left slots 215 and right slots 220. Aplurality of screws 225 (of which one is shown) extend through arespective one of slots 215, 220 or 221 and affix guide support 205 andguide support 210 to base board 201. Slots 215 and slots 220 extend fora length along the width of base board 201 to allows screw 225 to slidewithin slots 215, 220 to adjust the position of guide supports 205, 210relative to each other. In a preferred embodiment, each of slots 215,220 and 221 has a length of ⅛ of an inch allowing each guide support 205and guide support 210 to be moved towards the other or away from theother by ⅛ of an inch to accommodate a variety of filter caps 11 andcage bodies 65. Mounting holes 226 may be formed within base board 201to mount base board 201 at a desired location of a work bench, table orthe like. In a preferred embodiment, base board 201 is formed ofbakelite.

Guide supports 205 and 210 are substantially L-shaped when viewed on endand have a side wall 227 and 228 respectively. A slide surface 230 isformed at the top of side walls 227 and 228. An inner guide surface 229extends substantially orthogonally from slide surface 230 to provide acorner along the length of guide support 205. Similarly, guide support205 has a side wall 227, a slide surface 230 and an inner guide surface229.

A separator 231 includes a top 232 and a tapered surface 233 extendingtowards top 232 to form a substantially rectangular front end 234 ofseparator 231. Separator 231 is affixed to side wall 227 by screws 199at a position in which top 232 is substantially co-planar with slidesurface 230. Separator 231 is affixed in a similar manner. Guidesupports 205, 210 define a slide path for a cage top from which a filterretainer is to be separated. Guide supports 204, 205 are positioned soas to define a distance therebetween substantially equal to the width ofthe filter retainer. In a preferred embodiment, support guides 205, 210are made of plastic while separators 231, are made of machined aluminum.

During operation, a filter cap is placed on guide support 205 and guidesupport 210 in an inverted position so that the filter cap 11 is infacing relationship with base board 201 (not shown). The skirt of thecage top rests on slide surfaces 230, 240. The cage top is slid alongslide surfaces 230, 240 in the direction of arrow B towards theseparating edge 241 of separators 231, 242. Because the skirt slidesalong slide surface 230, 240 and because separators 231, 242 aresubstantially coplanar with slide surface 230, 240 separator edge 241 issubstantially disposed at the position where the filter retainer meetsthe cage top, acting as a wedge to separate the filter retainer from thecage top as the cage top is slid along the cage top slide path. Once acomplete pass has been made by the cage top, the filter retainer willfall to the surface of base board 201 allowing for easy removal of thefilter which had been previously retained between the filter retainerand cage top.

In providing a filter frame for an open-top cage with a perforatedfilter retainer which snaps onto a similarly perforated filter frame, afilter cap for an animal cage top provides a filter that may be easilyand quickly changed. By providing the filter above the perforated topwall of the filter frame, the filter may be replaced while the filterframe is on the cage to ensure that animals within the cage are notpermitted to escape while the filter is being replaced. In addition, thesubstantially rigid chew shield attached to the underside of the filterframe protects the filter cap from damage caused by animals within thecage. Moreover, by securing the filter retainer to the filter frame andthusly to the chew shield with an integrally formed attachment means,such as tabs and slots, no special tools are necessary to remove thefilter retainer or for replacing the filter.

Cage Dimension

Reference is now made to FIGS. 3 and 14, in which a particularconfiguration of an animal cage is shown which serves to maximize thenumber of animals which may be maintained in a cage rack system of agiven size. Each cage is required to provide a predetermined square areaper animal contained in the cage. It is possible to increase the areawithin the cage by extending the length of the cage, the depth of thecage. By providing increasing the bottom area by extending the cage, itis possible to increase the number of animals within the cage withoutincreasing the associated width or height so that rack and canopysystems as described above can accommodate both the conventional cageand the new larger cage. Preferably, the cage assembly 10 of the currentinvention has a square area of at least 140 square inches and is capableof supporting two large rats while remaining in compliance with the ILARand AWA regulations. Most preferably, the cage assembly 10 of thecurrent invention has a square area of 140.8 square inches.

Filter Cap Top Lock

Reference is now made to FIGS. 13-14 and 17-20, wherein a lockingmechanism, generally indicated at 25, constructed in accordance with thepresent invention to secure a variety of sized cages is depicted.Locking mechanism 25 locks a cage assembly 10 and includes a base member250 a releasable latching member 251. Latching member 251 is integrallyattached to base member 250 and when securing a filter cap 11 to a cagebody 65 is disposed in a locking position such that foot 252 andshoulder member 254 of latching member 251 are in close locking contactwith the lower surface of filter cap 11 and peripheral lip 83 (notshown). Filter lock 25 provides a secure seal for cage assembly 10through tension from foot 252 and the lower surface of filter cap 11 andperipheral lip 83. This tension can be easily released by an operator bypushing in a downward direction on latching member 251. By furtherproviding a locking mechanism with a base member which is easilydetachable by an operator between a locking and unlocked position, asimple mechanism is provided which easily and quickly allows securelocking and unlocking of a cage within a rack system with a minimum ofeffort and a minimum number of parts. In addition, by providing alocking mechanism which is mounted to a post of a rack system accessiblefrom the front of the rack system, a readily visible locking mechanismis provided which allows an operator to easily determine whether a cageis properly secured within the rack system.

Rotatable Feeder

Now referring to FIGS. 48-51, a second embodiment of cage assembly 10employing a rotable multiple dosage feeder 300 for a cage body 65 isalso provided. The rotatable multiple dosage feeder 300 includes a frame301 having a cage-interior side, a food holding member 302 rotatablymounted on the frame 301, and a food presentation member 303 disposed onthe cage-interior side of the frame 301. The food holding member 302holds a plurality of measured dosages of food or other substances, andat least a portion of the food holding member 302 extends to thecage-interior side of the frame 301. The food presentation member 303permits access to a single dosage of the plurality of dosages by ananimal within the cage 10. At least a portion of the food holding member302 is rotatable within the food presentation member so as to expose thesingle dosage of the plurality of dosages, while the food presentationmember 303 prevents access to any remaining dosages on the cage-interiorside of the frame 301. With carousel feeder the floor area is 124 sq.inches excluding carousel.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in the above construction withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

1. A filter top lock for locking a cage level barrier cage such that ananimal held within said cage can not remove the top of said cage from acage body, said filter top lock comprising: a base member; a releasablelatching member a foot member; and a shoulder member; wherein thelatching member is integrally attached to the base member and whensecuring a top of said cage to a cage body the foot and shoulder membersof said lock are disposed in a locking position such that foot andshoulder member are in close locking contact with the lower surface ofsaid top of said cage and a peripheral lip of said cage body; said lockcan be released by an operator by pushing in a downward direction onsaid latching member.
 2. The filter top lock of claim 1, wherein saidlock is comprised of a durable and semi-rigid plastic.
 3. An animalisolation and caging system comprising: a ventilated rack, said rackincluding at least one air exhaust plenum; at least one canopy disposedwithin said rack for ventilation of cages housed in a said caging systemwherein said rack is capable of supporting at least one cage levelbarrier cage within said rack below said at least one canopy whilemaintaining a gap between the top of said at least one cage and said atleast one canopy so as to permit air to be drawn into said air exhaustplenum from the interior of said at least one cage through the top ofsaid at least one cage; and a filter top lock, said filter top lockcomprising: a base member; a releasable latching member a foot member;and a shoulder member; wherein the latching member is integrallyattached to the base member and when securing a top of said cage to acage body the foot and shoulder members of said lock are disposed in alocking position such that foot and shoulder member are in close lockingcontact with the lower surface of said top of said cage and a peripherallip of said cage body; said lock can be released by an operator bypushing in a downward direction on said latching member.